A new study shows some cases of psoriasis respond to the placebo effect, offering new information on the amount of medication and types of treatments these kinds of skin conditions need.

Researchers have long wondered why placebos—fake medications—sometimes help sick patients get better. Now, a new study says placebos can help psoriasis patients get by on smaller doses of a steroid drug that dampens their immune systems.

The study authors, from the University of Rochester Medical Center in New York, think they may be able to develop other treatments that rely on the placebo effect to boost the power of lower doses of existing drugs. "Our study provides evidence that the placebo effect can make possible the treatment of psoriasis with an amount of drug that should be too small to work," lead investigator Dr. Robert Ader, a professor at the University of Rochester School of Medicine & Dentistry, said in a news release from the school. "While these results are preliminary, we believe the medical establishment needs to recognize the mind's reaction to medication as a powerful part of many drug effects, and start taking advantage of it."

There are limitations, however. Placebos can't help people who are unconscious or stimulate the release of substances in the body, such as insulin, Ader said.

The researchers tested creams on 46 patients with mild and moderate cases of psoriasis. One group got fully medicated creams, while others got mixtures that were partially medicated or received full doses only part of the time. In some cases, the patients seemed to do well despite not getting the full dose, suggesting a psychosomatic effect.

The study was published online Dec. 22 in the journal Psychosomatic Medicine.